Pull-through furnace for the continuous stress-relief annealing of rolled products in strip form



Nov. 8, 1966 E. ENGELHARDT 3,284,073

PULL-THROUGH FURNACE FOR THE CONTINUOUS STRESS-RELIEF ANNEALING OF ROLLED PRODUCTS IN STRIP FORM Filed D60. 28, 1964 2 Sheets-Sheet l 2 IE! El i:

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PULL-THROUGH FURNACE FOR THE CONTINUOUS STRESS-RELIEF .ANNEALING OF ROLLED PRODUCTS IN STRIP FORM Filed Dec. 28, 1964 2 Sheets-Sheet 2 Fig.3

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Inventor:

ERMA N EN-ELH RDT United States Patent 3 234,073 PULL-THROUGH FURNACE FOR THE CONTINU- OUS STRESS-RELIEF ANNEALING 0F ROLLED PRODUCTS IN STRIP FORM Erwin Engelhardt, Gelsenkirchen-Buer, Germany, as-

signor to Mannesmann Aktiengesellschaft, Dusseldorf, Germany Filed Dec. 28, 1964, Ser. No. 421,401 Claims priority, application Germany, Dec. 30, 1963, M 59,419 9 Claims. (Cl. 266-3) The invention relates to a pull-through furnace for the continuous stress-relief annealing of rolled products in strip form. It particularly concerns a furnace for annealing dynamo and transformer sheet strip, said furnace having in its interior supporting rollers arranged transversely of the direction of passage of the strip material.

It is known that coils, annealed as wound coils at elevated temperatures, are not free from stress after this annealing. When such coils are unwound, it is found that they are corrugated in consequence of their round fit during the annealing process. Due to the previous cold rolling of such coils, considerable stresses and corrugations may already be present, and these are not eliminated during annealing of the coils, even at elevated temperatures. To eliminate such unevennesses and stresses in the strip, the latter, after previous annealing or also directly after rolling, is subjected to stress-relief annealing in furnacessuitable for this purpose.

It is known that in the stress-relief annealing of such strip, the strip, or if several strips are concerned, the strips, which are conveyed over the rollers of such a furnace, are stretched solely by the tension produced by a brake in front of the furnace and by coiling after the furnace. The degree of stretch must here not exceed a certain value, because the magnetic value is thereby unfavourably affected. This stretching, particularly in view of the considerable length of the furnace, no longer su ffices for strips which have considerable bends, edge corrugation, so-called deep troughs and unequal sides on passage. In addition, in the event of considerable tension over the entire strip length in the furnace, longitudinal corrugations would be produced in the strips, and could then no longer be eliminated.

It is the aim of the invention to provide a device whereby even strongly deformed strips with bends, edge corrugations, so-called troughs and unequal sides can be stress-relieved by annealing without tension corrugations being produced, and without the magnetic value being unfavourably affected. By means of this device, a satisfactory plane strip is to be produced.

According to the invention, this is achieved by providing in the pull-through furnace, between each pair of strip supporting rollers, a straightening roller, engaging the top side of the strip and adjustable transversely of the direction of passage of the strip.

The strip is therefore passed not only over the rollers,

but also under one or more rollers. In this way, due to the better stretching obtainable, it is possible to produce a satisfactory plane strip since for continuous stressrelief annealing it is necessary that the roller should always engage the strip, the individual rollers must be replaceable upon the occurrence of fouling of their surface, without it being necessary to interrupt the annealing process and this can be achieved by axially displacing the rollers transversely of the furnace so as to bring into operation on each roller, a clean fresh surface. In the preferred arrangement there is provided in the pullthrough furnace as hereinbefore described in the direction of passage close in front of or behind the individual rollers of each roller set, rollers of a duplicate roller set preferably mounted at the same distance apart as the rollers of the first roller set. Preferably the rollers are mounted externally to the furnace by passing their ends through openings in the furnace wall. It is also preferred to construct each individual roller to have such an axial length as to provide two separate axially adjacent working faces.

With this construction of furnace and rollers, it is possible to proceed during operation such that first only one set of rollers engages the strip, each individual roller engaging the strip with one of its two working surfaces. As soon as the surface of these rollers has been fouled, so that the strip would be damaged, the second roller set is brought into engagement. After this has been done, the rollers of the first set can be lowered and shifted in the axial direction. The contaminated working surfaces of this roller set are then cleaned outside the furnace, and the rollers remain in this position for the time being until the working faces of the second roller set have become fouled, and the first roller set is brought into use, but now with its second working surfaces. The working method already described in the foregoing is then repeated for the second roller set, thus affording the advantage that operation can be continuous, while at the same time, rollers with satisfactory working surfaces are always available, and in addition it is found that the working-surfaces that have been standing-by are already preheated when they are put to use.

It is sometimes expedient to stress relieve the strip material by annealing in an atmosphere of protective gas. It is then necessary for the roller throughways in the furnace wall to be sealed by mechanical means and by protective gas supplied additionally at these points. For this purpose, close to the throughway through the furnace wall, each individual roller is surrounded by a sealing sleeve. Each sealing sleeve consists of two halves connected to an annular sealing disc. The latter encloses a flexible sealing diaphragm between its inner periphery and the sealing sleeve, being guided on its outer periphery in an annular guide fixed relatively to the furnace wall. The annular guide is fixed to a box, surrounding the throughway, and covered with a water-cooled annular sheet-metal cover on the bearing side of the roller, said box being provided with a protective gas inlet and enclosing a number of lamellae discs, secured alternately to its interior and to the sealing sleeve.

A constructional example of the invention is represented diagrammatically in the drawing, in which:

FIGURE 1 shows a pull-through furnace, viewed from one of its two long sides,

FIGURE 2 shows the furnace according to FIGURE 1 in plan,

FIGURE 3 shows a roller seal on such a furnace, in section,

FIGURE 4 shows this seal, viewed in the direction of the roller axis, the roller mounting and bearing having been omitted.

As will be seen in the drawing, FIGURE 1 shows a a pull-through furnace 1, in which a strip 2 is carried over a supporting roller 3, under a second roller 4, and then over a supporting roller 5 again. It has been found expedient to arrange these rollers 3, 4, 5, particularly however roller 4, which presses on the strip from above, for vertical adjustment by means of devices known per so. By this means, it is directly possible, instead of increasing the pull of the entire range, to influence the passage of the strip 2 to a greater or lesser degree by vertical adjustment of these rollers 3, 4, 5. It is then also possible, without increasing the pull, to produce better stretching for a short time as desired. Since, in such a process, it may frequently'happen that pimple formation occurs on the surface of the rollers in the furnace, thereby tending to damage the surface of the strips, the rollers 3, 4,

3 are so constructed that by means of a few manipulations, they may be moved very easily sideways out of the furnace and thus changed, without having to be completely dismantled.

FIGURE 2 shows such a furnace 1 viewed from above. The figure clearly shows that each of the furnace rollers 3, 4, 5 is provided in double length. At the ends of each roller 3, 4, 5 are bearings 6, 7, 8, for carrying the roller. While one part of each roller 3, 4, 5 is situated in the furnace 1, the other part projects by the same length laterally out of the furnace 1. By means of this arrangement, it is at once possible to change the roller parts rapidly, and to free the part of the roller affected by pimples and surface contaminations mechanically during its stay outside the furnace.

Operation with only one exchangeable roller 3, 4, 5 at one place has the disadvantage that during the change,

the cold roller part outside the furnace takes a few minutes after the change to reach the temperature prevailing in the furnace 1. During this heating-up time, the strip 2 running over the still cold rollers 3, 4, 5 would become corrugated and thereby useless. It is therefore of considerable advantage if instead of one roller always two rollers 3 and 3', 4 and 4', 5 and 5' are arranged adjacent each other in the furnace.

While both rollers are now situated in the furnace 1, only one roller 3, 4, 5 operates on the strip 2, which roller is set higher, or in the case of the pressure roller, lower. The second roller 3, 4, 5, which does not touch the strip, also rotates and has the temperature of the furnace. Before a change of roller, the second roller 3, 4', 5', is brought into contact with the strip 2, and only then is the roller, which was previously in contact with the strip, removed from the strip by being set higher or lower and then moved laterally. In this way, it is possible to ensure frictionless continuation of the passage of the strip without corrugations being produced on the through-running strip 2 by the previously described colder roller.

FIGURE 3,shows more particularly how sealing the adjustable rollers outside the furnace 1 is possible, so that such a furnace can also be operated with protective gas without the protective gas conditions in the furnace being thereby altered. It follows from the figure that each through-going roller, for example roller 3, is passed through an opening 115 in the furnace wall In and through a box 9 mounted on the latter. Each roller outside the said box is mounted on an adjustable holder 20. The box 9 has a water-cooled sheet-metal cover 10, on which is provided a guide 11 for an annular sealing disc 12. This sealing disc 12 is connected by links 13 to a sealing sleeve 15 embracing the roller 3 close to its mounting 14. A flexible sealing diaphragm 16 or the like is provided between the inner periphery of the sealing disc 12 and the outer periphery of a sealing sleeve 15.

On its end facing the opening 1b, the sealing sleeve 15 carries a number of lamellae, 17, which engage fan-like in counter-lamellae 18 arranged in the interior of the box 9. The sealing sleeve 15 and the lamellae disc 17 secured to it are halved in the diametrical direction, and the two par-ts of the sleeve 15 are pivoted to the links 13 in such a manner that the sleeve can be detached in a simple way from the roller 3. It is thereby possible to slide the roller 3, as already described with reference to FIGURE 2, in the longitudinal direction and then to close the sealing sleeve 15 again, without the protective gas atmosphere in the furnace undergoing any change. In addition, the said box 9, mounted outside on the furnace, is in each case provided with a protective gas supply 19, so that entry of air into the furnace is prevented with certainty.

This construction has the particular advantage that even in the case Of a furnace with a definite protective gas atmosphere, pimple formation on the rollers occurring heretofore in all furnaces can be made good decisively by simple changing of the rollers, without stopping or dismantling the rollers, and by removing the pimples outside the furnace. In this way, it is for the first time possible to carry out continuous operation also in the case of furnaces with a controllable protective gas atmosphere, without regard to pimple formation and hence to the difliculties arising through pimple formation on the surface of the strip.

I claim:

1. In a pull-through furnace for the purpose of continuous stress-relief annealing of rolled products in strip form the combination of: a straightening roller between two strip supporting rollers, the said roller being transversely disposed in the said furnace relative to the path of the strip, the said straightening roller engaging the top sideof the strip and each said roller being adjustable in the transverse direction, wherein each said roller has a length greater than twice the width of the said furnace, the said rollers being axially displaceable along their length at least for a distance equal to the width ofthe furnace.

2. The combination according to claim 1 wherein each said roller is adjustable in the vertical direction.

3. In a pull-through furnace for the purpose of continuous stress-relief annealing of rolled products in strip form the combination of duplicate sets of rollers comprising a straightening roller between two strip supporting rollers, each said roller having a length greater than twice the width of the said furnace, being transversely disposed in the said furnace relative to the path of the strip, along its length and adjustable in the vertical direction, the said straightening roller engaging the top side of the strip, the said duplicate sets being arranged so that each roller of a set is adjacent to a roller of the other set which has the same function.

4. The combination according to claim 3 including on the furnace means for creating an atmosphere of protective gas.

5. The combination according to claim 4 wherein the said means includes sealing means for each said roller.

6. The combination according to claim 5 wherein the said sealing means for each roller comprises, towards each axial end thereof, a sealing box which is fixed to the furnace wall and surrounds the respective roller and a split sleeve which is arranged on the roller, there being arranged a flexible diaphragm for sealing the annular space between the said box and the said sleeve.

7. The combination according to claim 6 further-comprising an annular sealing disc forming an external side wall of the said box, the said disc having attached to its external annular surface an annular guide which encloses the periphery of the said sealing diaphragm.

8. The combination according to claim 7 further comprising a plurality of interleaved lamellae discs fixed alternatively to the said box and to the said sleeve and arranged Within the said box.

9. The combination according to claim 7 further comprising means for providing a supply of protective gas to the interior of the said box including a duct through the wall of the box.

References Cited by the Examiner UNITED STATES PATENTS 747,779 12/1903 Ryan 266-25 FOREIGN PATENTS 401,584 11/ 1933 Great Britain.

JOHN F. CAMPBELL, Primary Examiner. M. L. FAIGUS, Assistant Examiner. 

1. IN A PULL-THROUGH FURNACE FOR THE PURPOSE FOR CONTINUOUS STRESS-RELIEF ANNEALING OF ROLLED PRODUCING IN STRIP FORM THE COMBINATION OF: A STRAIGHTENING ROLLER BETWEEN TWO STRIP SUPPORTING ROLLERS, THE SAID ROLLER BEING TRANSVERSELY DISPOSED IN THE SAID FURNACE RELATIVE TO THE PATH OF THE STIP, THE SAID STRAIGHTENING ROLLER ENGAGING THE TOP SIDE OF THE STRIP AND EACH SAID ROLLER BEING ADJUSTABLE IN THE TRANSVERSE DIRECTION, WHEREIN EACH SAID ROLLER HAS 